The present invention relates to a two phase microbial process for the preparation of compositions containing .gamma.-hexalactone and, optionally also 2-pentanone. In a further aspect, the present invention relates to products produced by the microbial process.
In a still further aspect, the present invention relates to organoleptic uses of said products.
.gamma.-Hexalactone is also know as .gamma.-caprolactone; ethyl butyrolactone; .gamma.-ethyl-n-butyrolactone; hexanolide-1,4; 4-hydroxy hexanoic acid .gamma.-lactone or tonkalide.
It is characterized by a warm, herbaceous, sweet tobacco-like, coumarinic odor and a sweet, powerful, warm-herbaceous, coumarin-caramel taste. Widely used in perfume composition and for flavoring purposes, it is an important material in the flavor and fragrance industry (Arctander, Perfume and Flavor Chemicals II, 1969).
In today's market, it is frequently desirable to identify flavor components of food items as being "natural flavors." It is generally recognized in the industry that a flavor compound having been prepared by microbial processes can be designated as a natural product and therefore have an important place in the commercialization of products containing them. As a result, the industry has devoted considerable time and effort to develop methods for the production of flavoring components and, in particular, for the production of lactones which can be called "natural."
Thus, as an example of such prior developments, a method for preparing certain optically active .delta.-lactones and the corresponding hydroxy carbocyclic acids by microbial reduction of ketocarboxylic acids is shown in U.S. Pat. No. 3,076,750.
Investigations reported in the Journal of Biochemistry, 54, pages 536-540 (1963) relate to metabolism of ricinoleic acid by some Candida strains and show that .gamma.-hydroxydecanoic acid is an intermediate in the oxidative degradation of ricinoleic acid. In a number of such prior disclosed methods, the processes were not entirely satisfactory because of the toxicity of certain components to the microorganism.
A method of producing optically active .gamma.-hydroxydecanoic acid by culturing or incubating a microorganism capable of hydrolyzing castor oil and effecting .beta.-oxidation of the resulting hydrolysate in the presence of castor oil to produce .gamma.-hydroxydecanoic acid is shown in U.S. Pat. No. 4,560,656.
This prior document also discloses a method of producing optically active .gamma.-hydroxydecanoic acid by enzymatically hydrolyzing castor oil using lipase to form an enzymatic hydrolyzate and culturing a microorganism capable of effective .beta.-oxidation of the enzymatic hydrolyzate in the presence of the hydrolyzate to produce .gamma.-hydroxydecanoic acid. Similarly, a way of culturing or incubating the microorganism capable of hydrolyzing castor oil and a microorganism capable of affecting .beta.-oxidation of the castor oil hydrolyzate in the presence of the castor oil to produce .gamma.-hydroxydecanoic acid is also shown in that document.
European Published Patent Application 258993 of Apr. 9, 1988 discloses a process for the production of optically active .gamma.-hydroxydecanoic acid suitable for conversion to optically active .gamma.-decalactone.
Microbial production of natural .delta.-dodecalactone from Massoi bark oil was discussed by van der Shaft et al. in Applied Microbiology and Biotechnology (1992) Vol. 36, pages 712-716.
The usefulness of yeast for reduction reactions in general, including conversion of Massoi lactone is referred to by N. J. Turner in Chemistry & Industry, Aug. 1, 1994, pages 592, et seq.
Japanese Application 09 031071-A discloses production of (R)-(-)-massoi lactone by incubating a microorganism.
More recently, in U.S. Pat. No. 5,128,261, 5-decanolide and 5-dodecanolide have been shown to be produced from a series of strains of yeast in a fermentation reaction by carrying out a biocatalytic reduction of the corresponding natural unsaturated 5-olides.
The production of .gamma.-lactone flavor additives using the genus Pityrosporum is shown in Labows et al. U.S. Pat. No. 4,396,715.
The genus Amastigomycota is shown to produce methyl ketones by aerobic biotransformation of C.sub.6 -C.sub.11 fatty acids in Creuly, et al., U.S. Pat. No. 4,957,862.
Another process for producing .gamma.-lacotones and .delta.-lacotones is shown in Page et al., U.S. Pat. No. 5,032,513. The fungus of the genus Mucor is used for this purpose.
Such prior methods are said to be economically attractive but there is a constant need for improvement of yields and conversion which is addressed in this invention.
In the flavor and fragrance art the need has risen for the development of more efficient production of naturally occurring lactones which have heretofore been found to be useful and necessary in the creation of flavor formulation used in augmenting or enhancing the aroma or taste of such items as foodstuffs, chewing gums and toothpastes, and also useful in augmenting or enhancing the aroma of perfume compositions such as colognes, perfumed articles either in solid or liquid state as, for example, ionic, cationic, nonionic or zwitterionic detergents, perfumed polymers, fabric softener compositions, fabric softener articles, hair preparations, cosmetic powders and the like.
It is therefore an object of the present invention to provide a new and improved method for preparing .gamma.-hexalactone which has been found to be suitable for a wide variety of purposes in a more efficient manner to produce a higher yield and greater conversion.
Another object of the present invention is to provide a process for the formation of a plurality of flavor compounds.